1. Field
The present invention relates to a radiator cleaning treatment method and a method for cleaning a radiator.
2. Description of the Related Art
For example, a polymer electrolyte fuel cell includes an electrolyte membrane-electrode assembly (MEA) in which an electrolyte membrane made of a polymer ion-exchange membrane has an anode electrode on one face thereof and a cathode electrode on the other face thereof. The electrolyte membrane-electrode assembly is sandwiched between separators to constitute a power generation cell (unit cell). Typically, a predetermined number of power generation cells are stacked and built into a fuel cell vehicle (such as a fuel cell electric automobile) as an onboard fuel cell stack, for example.
An electric vehicle such as a fuel cell vehicle needs to satisfy the regulations regarding electric safety such as ECE-R100 and FMVSS305. For this reason, the entire electric power train is required to have ground fault resistance meeting the regulatory requirements. To this end, setting is made so that the sum of each device's allotted resistance (ground fault resistance between each device and chassis GND which is the ground potential of the fuel cell vehicle) exceeds the ground fault resistance required by the regulations.
For example, a fuel cell stack has high-voltage devices such as a gas system, a stack peripheral system, and a cooling system, and each of these devices is set with its allotted resistance. In the cooling system, devices such as a radiator, a coolant pump, and an auxiliary device are grounded to chassis GND. Thus, in order for the cooling system to achieve ground fault resistance equal to or larger than its allotted resistance, it is required to manage the coolant conductivity and appropriately set layout of piping (such as a pipe diameter and a pipe length) to each device grounded to the chassis GND.
A fuel cell system disclosed in Japanese Patent Application Publication No. 2014-157832 is known as equipment having this kind of cooling system. This fuel cell system includes: a first coolant system that is configured to circulate and supply coolant through and to a first circulation path including an in-cell coolant passage inside a fuel cell and a coolant cooling device; and a second coolant system that is configured to circulate and supply coolant through and to a second circulation path including the in-cell coolant passage and an ion exchanger. In this system, for control of circulation of coolant by the first coolant system and the second coolant system, the second coolant system circulates and supplies coolant through and to the fuel cell for a predefined priority period in advance upon activation of the fuel cell.
From the start of the priority period, the entire coolant passing through the second circulation path of the second coolant system repeatedly passes through the ion exchanger and ions in the coolant are removed there after circulating through the in-cell coolant passage of the fuel cell. Accordingly, the coolant whose conductivity has been lowered swiftly in the priority period circulates through the in-cell coolant passage of the fuel cell. Thereby, a reduction of insulation properties of the fuel cell caused due to the existence of the coolant can be avoided early and effectively.